Articles by John Siegenthaler, P.E.

A recent design approach for air-to-water and water-to-water heat pumps is "direct-to-load" piping. This method utilizes an inverter-driven scroll compressor, which operates across a wide range of speeds and can handle on/off cycling without the high inrush current typically seen in fixed-speed compressors.

Most heat pumps in North America extract heat from outside air to warm interiors, which is why we call them "air-to-air" heat pumps. However, this term is incomplete, as heat pumps can also provide comfort without relying on forced air delivery.

Last month's column discussed piping for air-to-water heat pumps. A 2-pipe system allows staging but not simultaneous heating and cooling, while a 4-pipe system with motorized valves enables both modes of operation.

Last month, we started with an air-to-water heat pump for space heating and added an auxiliary heat source and chilled water cooling. This month, we’re adding domestic water heating, similar to last month’s setup.

Air-to-water heat pumps, especially for larger systems, can be used in stages for efficient temperature control and flexibility, utilizing variable-speed compressors and specific piping setups to manage heating and cooling loads.

A review of a flawed hydronic heating system uncovers critical errors, such as improper circulator placement and restrictive mixing valves, leading to uneven warmth and corrosion issues. This underscores the need for proper design and installation in hydronic systems.

Hydronically-heated concrete floor slabs offer comfort but can be slow to warm up. A proposed solution uses a heat pump and variable-speed circulators to provide rapid heating through air handlers, ensuring quick warmth during cool days while maintaining energy efficiency.

As government electrification target dates loom in the near future, and power transmission systems get pushed closer to their limits, utility companies continue implementing ways to manage peak demand.

In 1986, I installed a 1.5-ton geothermal heat pump in my home using two 500-foot horizontal HDPE earth loops. After digging a trench, I connected the loops to the pump and opted for a 2 HP swimming pool pump to fill and flush the system, as a garden hose couldn't provide the needed flow rate.

A project needs medium- and low-temperature radiant floor panels. The installer proposes using a mod/con boiler with a 1-inch tempering valve for lower temperatures and plans to pipe the entire system with 1-inch tubing. What potential issues could arise from this design?